The fully threaded model of Zulip allows you to follow conversations that you care about and ignore the ones you don't.

Cons:

Nothing I can think about. It's insanely great :)

Zulip is built by keeping productivity in mind. Each conversation in Zulip has a topic. This allows you to take part in more than one conversation at the same time. This also make catching up on conversations efficient as compared to cSlack, Mattermost etc where you have to scroll through hundreds or thousands of messages to figure out what is going on. Zulip is the most active open source chat application in GitHub and has 350+ contributors from all across the world.

I have been using Zulip only for three months, but I can't help wondering how I managed to get anything done without it. Everything about this chat is so thought through that I consider it essential to stay productive. Organizing all conversations into streams and topics makes it clear what each discussion is all about, so you can always mute everything that's irrelevant to you at the moment, and focus on important things. I didn't initially appreciate the full-text search, but now I regularly use it to find all the places where a particular subject was discussed. It's almost impossible to lose something with Zulip.

In addition to that, Zulip for macOS is a total eye candy. I like the minimalistic design, the colors, everything about it! I couldn't have wished for a better app. I also have Zulip for iOS, but I don't use it as much. I think it's kind of difficult to take advantage of all the great Zulip features on a small screen.

There are few minor bugs present in application, but it can easily be filed at Github and gets quickly fixed.

Zulip is a fast and powerful group chat application with many unique features and more than 60 integrations. Above all it's an open source project makes it even better, as you can directly contact the developers about the issue you face, features you're missing or want to be improved and even file them at github.com/zulip/zulip/issues.

- slightly steeper learning curve as compared to other group chats, but better user experience long-term

Zulip is a great group chat, especially for communities. Whenever you come back, you can easily go through topics and streams - it's easy to narrow down to relevant conversations and just as easy to get a general view of all the messages. Each topic has it's own URL, which makes it easy to get back to a conversation. Also, search is quick and relevant.

One of the communities that uses Zulip is the Recurse Center - check out their blog post https://www.recurse.com/blog/112-how-rc-uses-zulip.